Reports on HIV/AIDS: 1990

NOVEMBER 30, 1990, MMWR, Vol. 39, RR-16 [inclusive page numbers]
2. Back-calculation models should incorporate all available AIDS surveillance data,
including data for persons diagnosed as having AIDS after mid-1987. The
models will, however, require modifications to allow for changes in the
distribution of the incubation period that reflects the results of early therapy.
3. Separate back-calculation estimates of prevalence should be made for distinct
transmission categories and demographic and geographic subgroups.
4. The statistical imprecision of estimates of the distribution of the incubation
period should be incorporated into the back-calculation models. Studies should
be carried out to characterize more accurately the distribution of the incubation
period in populations other than homosexual men (e.g., IVDUs and perinatally
infected infants).
5. Estimates of the statistical precision of back-calculations should accompany all
point estimates-with the sources of error clearly stated. Additional uncertainty
should be assessed by sensitivity analysis and synthesized into an overall
estimate of uncertainty.
6. Researchers using back-calculation should be encouraged to share informally
their adjusted data on AIDS incidence before publication. Sharing these data
will make it easier to determine whether differing results are caused by different
adjustments for reporting delays or by different methodologies.
Additional recommendations included the following:
1. For direct estimation of total HIV prevalence, the direction and impact of the
biases inherent in observed seroprevalence data from CDC's seroprevalence
surveys-especially those from childbearing women-should be further evaluated.
2. Results of the feasibility phase of the National Household Seroprevalence
Survey (NHSS) should be reviewed, and information that could be collected to
give more precise estimates of HIV prevalence and/or help refine model-based
projections should be identified.
3. Further analysis should be done to make minimum-and, if possible,
maximum-estimates of the number of new infections per year (annual HIV
incidence), using both observed seroconversion data and back-calculation
models.
4. Analytic approaches should be explored for inferring incidence from serial
cross-sectional prevalence data as the information becomes available from
CDC's seroprevalence surveys.
Actions taken since meeting
1. A description of the methods used in CDC's HIV seroprevalence surveys was
published (18).
2. In October 1990, a summary of descriptive data from CDC's family of seroprevalence surveys was published (19).
SPECTRUM OF IMMUNOLOGIC DEFICIENCY AMONG
HIV-INFECTED PERSONS
Monitoring the CD4 + cell counts of persons with HIV infection provides a measure
of HIV-related immune dysfunction. To help quantify HIV-related morbidity and to

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